Genesis 15:8

And he said, "LORD God, whereby shall I know that I shall possess it?"

And Zacharias said unto the angel, "Whereby shall I know this? Seeing that I am old, and my wife well stricken in years."

And Gideon said unto God, "If thou wilt save Israel by my hand as thou hast said:

Then said Hezekiah to Isaiah, "What is the sign that the LORD will heal me, and that I shall go up into the house of the LORD the third day?"

Show some token upon me for good, that they which hate me may see it and be ashamed; because thou, LORD, hast helped me, and comforted me.

"Ask thee a sign of the LORD thy God, from alow beneath, or from on high above."

And he said unto his eldest servant of his house which had the rule over all that he had, "Put thy hand under my thigh

Lo, I stand here by the well of water and the daughters of the men of this city will come out to draw water:

And he answered him, "If I have found grace in thy sight, then show me a sign, that thou art the LORD that talketh with me.

if they say on this wise to us, 'Tarry until we come to you,' then we will stand still where we be and not go up unto them.

Then said Mary unto the angel, "How shall this be, seeing I know not a man?"

Treasury of Scripture Knowledge